Electrical measuring instrument.



PATENTED AUG. 1, 1905.

T. DUNCAN. ELECTRICAL MEASURING INSTRUMENT.

v No. 796,051.,

APPLICATION FILED AUG. 26; 1801.

M OTOR.

MIWIIQ 1:7 CHARGING CIRCUIT INVENTOR. Tramma LI'HBM zi f;

PATENT OFFICE.

THOMAS DUNCAN, OF oHioAe iLLiNoI s.

ELECTRICAL MEASURING INSTRUMENT.

Specification of Letters Patent.

Patented Aug. 1, 1905.

. Applicationfiled Au ust 26, 1901. Serial No. 73,326.

To all whom it may concern:

Be it known that I, THoMAs DUNCAN, a citizen of the United States, residing at Chicago,-

in the county of Cook and State of-Illinois,

have invented a certain new and useful Improvement in Electrical Measuring Instru unit of load or energy upon an increase in the rate of discharge.

In the use of storage batteries it is well known that the output of the battery will al- Waysbe less than the energy stored therein and that the battery loss will increase upona suflicient increase in the rate of battery discharge. For example, (supposing the battery to be a one-hundred-volt battery,) if the battery is charged one hundred thousand watthours at its normal ratesay ten thousand watts for ten hours the total discharge at the same rate which can be made available without harm to the battery will not be more than about-eighty percent. of the energy charged into the battery with some makes of battery, this battery loss varying with diiferent makesthat is, the battery will eflectively operate at one hundred amperes per hour for eight hours, giving out eight hundred ampere-v hours (equivalent to eighty thousand watthours of energy) after having received one thousand ampere-hours, (equivalent to one hundred thousand watt-hours.) If the rate of discharge is increased, the total output will be diminished. For example, with certain makes of battery the energy discharged will not be over about seventy per cent. if the rate is increased to one hundred and forty amperes,

sixty per cent. if the rate of discharge is doubled, and forty per cent. if the rate of discharge is quadrupled. 1 i

I have provided an instrument that is adapted to compensate for the varying battery losses due to the varyingrates of discharge, so that the user of the battery may know when the available energy in the battery is spent. Or-

' dinarily a meter associated with a storage battery that is discharged at varying rates will indicate the presence of. more energy in the battery than actually exists. The meter of my invention is also adapted to measure the energy that is being stored in the battery, the meter when thus associated with the charging source of current being operatively dissociated from the means that cause the meter to operate at varying rates of speed per unit of load or energy at different rates of discharge.

The meter of my invention is particularly adapted for use in connection with motors employed in operating motor-vehicles, where the rate of discharge is not constant, but is liable to be changed at any time. The preferred means for causing this variation in the rate of operation of the meter consists in the provision of a variable load that is automatically controlled by means subject to the variable volume of current flowing from the battery. 4 This load is preferably in the form of an electromagnetic drag acting upon a disk coupled with the rotating element of the meter and having a winding subject tothe pressure of the battery. This electromagnet is also provided with a winding in series with the battery, which acts in opposition to the shunt-winding in a degree dependentupon the flow of current or rate of discharge to decrease the force of the drag and permit the speed of the disk and rotating element of the meter to increase as the rate of discharge increases. An added or supplemental winding of the meter is also included in circuit when the battery is connected with the translating means to increase the torque of the meter.

I will explain my invention more fully by referenceto the accompanying drawing, which is a diagrammatic view of a storage-battery system with the meter .of my invention asso ciated therewith.

In the drawing a storage battery 1 is illustrated, having mains 2 and 8. The main 2 is provided with bifurcated branches 1 5, terminating in contacts 6 and 7, while the main 3 terminates in a pivotal mounting 8, upon which a switch-blade 9 of a switch 10 is secured. A second switch-blade 11 of the switch '10 is also placed upon apivotal mounting 12. Terminals of a charging-circuit 13 and 14 are illustrated. Terminals 15 and 16 of conductors leading to translating means, as the motor of a motor-vehicle, are also illustrated. When the switch 10 is thrownto the left, the charging-machine or source of current is throwninto circuit with the storage battery,

When the switch is'thrown to the right, the storage battery is thrown into circuit with the translating means.

I have illustrated a meter having a currentwinding included in the main 2, this currentwinding being subdivided into load-coils 17 17. The meter is also provided with a pressure-winding 18, included in bridge between the battery leads or mains. These windings of the meter are constantly in circuit with the battery irrespective of its association with the charging machine or the translating means. The meter-winding 18 is preferably in the form of an armature and is mounted upon a spindle 19, at the lower end of which is provided a disk 20, arranged within the fields of a damping-electromagnet 21 and a permanent magnet 22, the meter thus constituting a wattmeter, though I do not wish to be limited to this type of instrument. The shaft 19 also carries the commutator 28, against which bear brushes 24 24, that serve to include the armature of the meter in circuit, a choking and adjusting resistance 25 being also included in circuit with the armature.

The meter is provided with gearing at its upper end to actuate the measuring-index 26, which by cooperation with a suitable readingscale serves to indicate the amount of energy stored in the battery in charging and remaining in the battery in discharging.

The winding of the electromagnet 21 is preferably included in series with a choking and adjusting resistance 27 and in bridge of the battery mains or loads to be subject to the battery potential.

The core of the magnet 21 is provided with a winding 28, that is connected in circuit with the branch conductor 5. A supplemental field-winding 28 for the meter is also included in the conductor 5, preferably in series with the winding 28.

When the switch is thrown to the left in charging the battery, both windings of the magnet 21 are cut out of circuit, as well as the supplemental field-winding or load-coils 28, the main meter circuit being completed by way of the branch conductor 4. When the winding 28 is out of circuit, the torque of the meter is reduced per unit of load or energy while the battery is being charged. To compensate for the load removed from the meter by the exclusion of the windings of the magnet 21 from circuit, I provide a torque-reducing coil 29, that is included in circuit with the armature when the switch is thrown to the left, so that a further-redueed torque accompanies the reduced load when the energy that is being stored in the battery is measured.

When the switch is thrown to the right, the branch conductor 4 is diseonnected,whereupon the meter-circuit is completed by way of the conductor 5 and the supplemental magnet-winding 28. WVith this adjustment of the switch 10 the torque-reducing resistance 29 is cut out of circuit, both windings of the electromagnet 21 being then included in circuit. The torque of the meter is increased by the supplemental winding 28, producing a field varying with the current.

The force of the electromagnetic drag due to the magnet 21 depends upon the difference in potential between the battery-terminals, and as that difference becomes less and less as the discharge proceeds the consequent drag will also decrease. The winding 28 exerts an opposing or neutralizing effect upon the main shunt-winding of the magnet 21, cffecting a corresponding reduction in the drag. As the magnetization due to this winding 28 varies with the amount of current flowing from the battery, the degree that the braking action is reduced will depend upon the rate of battery discharge. A large flow of current due to a high rate of discharge will obviously decrease the drag to a proportionately greater extent than a smaller How of current due to a lesser rate of discharge, and by proper proportioning and calibration the meter may in this manner be made to compensate for the varying inefficiency of the battery throughout its entire range of operation. The current through the field-winding 28 as it varies will produce a modification of the torque, assisting the magnet-winding in its function of modifying the rate of operation of the meter per unit of load or energy according to the rate of battery discharge.

It will be observed that 1 have provided an electric meter havinga retarding system comprising a permanent magnet prod ucing a constant magnetization and a diii'crentiallywound magnet one of whose windings is in the load-circuit, beingin series with the loadcoils of the meter, and the other and opposing winding in, the potential circuit, the strength of such differentially-W011 nd magnets becoming weaker as the load increases.

While I have herein shown and particularly described the preferred embodiment of my invention, it is obvious that changes may readily be made without departing from the spirit thereof, and I do not wish, therefore, to be limited to the precisedisclosures herein set forth; but,

Having thus described my invention. I claim as new and desire to secure by Letters Patent- 1. The combination with a storage battery, of a meter for measuring energy discharged, means for operating the meter at varying rates of speed per unit of load or energy, according to varying rates of discharge, a supplemental current-winding for the meter, and means for excluding the same from circuit, substantially as described.

2. The combination with a storage battery, of a meter for measuring energy discharged, means for operating the meter at increased rates ofspeed per unit of load or energy upon corresponding increases in the rate of discharge of the battery, a supplemental current-winding for the meter, and means for excluding the same from circuit, substantially as described.

3. The combination with a storage battery,

of a meter for measuring energy discharged, a load for the meter, means for decreasing the load upon an increase in the rate of discharge to increase the rate of operation of the meter per unit of load or energy, a supplemental current-winding for the meter, and means for excluding the same from circuit, substantially as described.

4. The combination with a storage battery, of a meter for measuring battery discharge, provided with a damping-disk, a magnet Within whose field the said disk is located, means for decreasing the force of the field of the first aforesaid magnet upon an increase in the 'rate of battery discharge to increase the rate of operation of the meter per unit of load or energy, a supplemental current-winding for the meter, and means for excluding the same from circuit, substantially as described.

5. The combination with a storage battery, of a meter for measuring battery discharge, provided with a dampingdisk, a magnet within whose field the said disk is located,

.and having a winding in circuit with the battery for producing a counter-magnetizing effect to reduce the force of the magnet to decrease the load upon the meter and increase the rate of operation of the meter per unit of load or energy, asupplemental current-winding for the meter, and means for excluding the same from circuit, substantially as described.

6. The combination with a storage battery, of a meter for measuring battery discharge, provided with a damping disk, a magnet within whosefield the said disk is located, a winding-for the magnet subject to the battery potential, a second winding for the magnet opposing the pressure-winding and included in series with a battery, whereby the opposing eifect is increased upon an increase in the rate of battery discharge to lessen the load upon the 'meter to cause the meter to operate at an increased rate of speed per unit of load or energy, a supplemental current-winding for the meter, and meansfor excluding the same from circuit, substantially as described.

7. The combination with a storage battery, of an electric meter provided with an electromagnetic drag energized by a winding in series with the battery, a supplemental currentwinding for the meter, and means for excluding the same from circuit,substantially as described.

8. The combination with a storage battery, of a meter for measuring battery discharge, provided with a damping disk, a magnet WithiIlWllOSG field the said disk is located, a

opposing the pressure-winding and included in series with a battery, whereby the opposing effect is increased upon an increase in the rate of battery discharge to lessen the load upon the meter to cause the meter to operate at an increased rate of speed per unit of load or energy, a supplemental current-Winding for the meter, means for-excluding the wind- 1ngs of the said electromagnet and the supplemental meter-winding from clrcuit when the storage battery is connected with the charging machine, said means also serving for including'the said windings in circuit when the storage battery is connected with the translating means, and means for compensating for the removal of the said magnet-Wind ings when the battery is connected with the charging-machine, substantially as described.

9. The combination with astorage battery, of a meter for measuring battery discharge,

provided with ada'mping-disk, a magnet with- Y in whose field the said disk, is located, a winding for the magnet subject to the battery potential, a second winding for the magnet op posing the pressure-winding and included in series with a battery, whereby the opposing effect is increased upon an increase in the rate of battery discharge to lessen the load upon the meter, to cause the meter to operate at an increased rate of speed per unit of load or energy, a supplemental current-winding for the meter, means for excluding the windings of the said electromagnet and the supplemental meter-winding -from circuit when the storage battery is connected with the charging-machine, said means also serving for including the said windings in circuit when the storage battery is connected with the translating means, and means for reducing the torque of the meter when the battery is connected with the charging-machine to compensate for the removal of the said magnet-windings when the battery is connected with the charging-machine, substantially as described.

10. The combination with a storage battery, of a meter for measuring battery discharge, provided with a damping-disk, a magnet within whose field the said disk "is located, a winding for the magnet subject to the battery potential, a second winding for the magnet opposing the pressure-winding and included in series with the battery, whereby the opposing effect is increased upon an increase in the regular battery discharge to lessen the load upon the meter tocause the meter to operate at an increased rate of speed per unit of load or energy, a supplemental current-winding for the meter, a torque reducing resistance, and means for excluding the windings of the said electromagnet and the supplemental meterwinding from circuit when the storage bat- &

windings in circuit when the storage battery is connected with the translating means, said means also serving for including the torquereducing resistance in circuit With the meter When the storage battery is connected with the charging-machine to compensate for the removal of the said electromagnetic windings, substantially as described.

11. The combination with a storage battery, of a meter for measuring energy discharged, means for operating the meter at varying rates of speed per unit of load or energy, according to the varying rates of discharge, and a supplemental current-Winding in the meter, substantially as described.

12. In an electric meter, a retarding system comprising a permanent magnet producing a constant magnetization, and an electromagnet whose strength becomes Weaker as the load increases.

13. In an electric meter, a retarding system comprising a permanent magnet producing a constant magnetization, and a diflercntially- Wound magnet one of Whose windings is in series with the load-coils of the meter.

14. In an electric meter, the combination with a damping-disk and its permanent magnet, of an electromagnet having two opposing windings, one in the potential-circuit and the other in the load-circuit.

In witness whereof I hereunto subscribe my name this 16th day of August, A. D. 1901.

THOMAS DUNCAN.

Witnesses:

GEORGE L. CRAGG, HERBERT F. OBERGEELL. 

